Fix even more crashes. To help identify remaining crashes now and in the future, I have made the ...

views/widget/widget_delegate.h

Index: views/widget/widget_delegate.h
===================================================================
--- views/widget/widget_delegate.h	(revision 89357)
+++ views/widget/widget_delegate.h	(working copy)
@@ -135,8 +135,8 @@
   virtual void OnWindowEndUserBoundsChange() {}
 
   // Returns the Widget associated with this delegate.
-  virtual Widget* GetWidget();
-  virtual const Widget* GetWidget() const;
+  virtual Widget* GetWidget() = 0;
+  virtual const Widget* GetWidget() const = 0;
 
   // Returns the View that is contained within this Widget.
   virtual View* GetContentsView();